The rebuilding of Darlington’s Unit 2 reactor is officially underway, Ontario Power Generation reported on July 9, as staff begin installing new calandria tubes (CTs). Part of the fuel assembly, replacement of these 480 CTs, signals the start of physically rebuilding the reactor with new components
Work to refurbish the reactor began in October 2016, OPG explains. First, the reactor was defuelled, and then isolated from the station’s other three operating units. This was followed by the disassembly phase, which involved taking it apart, component by component.
“We’ve spent the last several weeks inspecting the remaining components, including the calandria vessel, and cleaning and conditioning all other areas of the reactor, to allow us to start CT installation,” said Dietmar Reiner, Senior Vice President, Nuclear Projects. “We are ready to rebuild.”
The Canadian-designed CTs are manufactured in Ontario by Cameco, OPG’s communique continues. They are prepared in a clean room environment at the Darlington Energy Complex to guard against foreign material, then transported to the Unit 2 airlock before being taken in to the vault. There, they will be installed by a team made up of boilermakers and millwrights, with support from Engineering, Quality Control and Radiation Protection.
This work is scheduled to take 103 days, and wrap up in October. This leads into installation of the remainder of the fuel channel components, including end fittings, annulus spacers and pressure tubes.
“It’s no easy task, but the right team is in place to complete the work safely, with quality, on time and on budget,” said Mike Allen, Senior Vice President, Refurbishment.
“It will require precise control with every task, every torque and every weld,” he said. “Safety and quality workmanship will allow us to complete refurbishment of Unit 2, allowing it to continue providing clean reliable power for Ontarians for the next 30 years.”